javascript - 无法实现模块模式

Question

我正在尝试从 Douglas Crockford 的“Javascript:The Good Parts”一书中复制一些代码。思路是使用闭包进行对象封装，避免Javascript固有的全局变量。

var serial_maker = function (  ) {

// Produce an object that produces unique strings. A
// unique string is made up of two parts: a prefix
// and a sequence number. The object comes with
// methods for setting the prefix and sequence
// number, and a gensym method that produces unique
// strings.

    var prefix = '';
    var seq = 0;
    return {
        set_prefix: function (p) {
            prefix = String(p);
        },
        set_seq: function (s) {
            seq = s;
        },
        gensym: function (  ) {
            var result = prefix + seq;
            seq += 1;
            return result;
        }
    };
}(  );

var seqer = serial_maker(  );
seqer.set_prefix = 'Q';
seqer.set_seq = 1000;
var unique = seqer.gensym(  );    // unique is "Q1000"

Chrome 正在拾取错误:

Uncaught TypeError: Property 'serial_maker' of object [object DOMWindow] is not a function (anonymous function)

我做错了什么？

编辑:我应该说这段代码完全是从书中复制粘贴的......

Answer 1

您正在尝试将函数的结果作为函数执行，并且正在为函数赋值。尝试:

var seqer = serial_maker;
seqer.set_prefix('Q');
seqer.set_seq(1000);
var unique = seqer.gensym();

另见 jsFiddle